Thermo-colorable record copy sheet and coating composition



March 1956 JAMES-*KE-JEN CHENG 3,242,122

THERMOCOLORABLE RECORD COPY SHEET AND COATING COMPOSITION Filed Sept. 18, 1961 2 Sheets-Sheet 1 F 24 (INFRA RED) FIG.) 22

2O (BASE WEB OF PAPER) 2| (THERMO-SENSITIVE COATING) 23 (INFRA RED ABSORBING DATA (INFRA- RED NON-ABSORBING PAPER) FIG. 2

\ 24 (lNFRA-RED) INVENTOR JAMES KE-JEN CHENG HIS ATTORNEYS March 22, 1966 JAMES-KE-JEN CHENG 3,242,122

THERMO-COLORABLE RECORD COPY SHEET AND COATING COMPOSITION Filed Sept. 18, 1961 2 Sheets-Sheet 2 24 ('NFRA'RED) 2| (THERMO-SENSITWE REAR SURFACE CHARACTER NOT REPRODUCED ON COATING 2| INVENTOR JAMES KE'nJEN cHENs BY 41 HIS ATTORNEYS United States Patent 3,242,122 THERMG-COLGRABLE RECORD COPY SHEET AND CUATING (ZOMPGSITION James Ke-Jen Chang, Dayton, Ohio, assignor to The National Cash Register Company, Dayton, Ohio, a corporation of Maryland Filed Sent. 18, 1961. Ser. No. 138,775 8 Claims. (Cl. 260-296) This invention relates to a thermo-icolorab-le record copy sheet consisting of a base web, such as paper, coated with a norm-ally substantially colorless coating that assumes a color where heated to temperatures used in ordinary thermognaphic printing, and to a composition for coating such a sheet.

The copy sheet is adapted especially fior use with a master sheet containing data to 'be copied therefrom, which data consists of ink characters which absorb infrared radiation and thereby become heated differentially to the rest of the master sheet, whereby, by placing the novel copy sheet in contact with the master sheet and applying infra-red radiation to such two-sheet system, the data characters are heated directly, or reflexly by transillumihation through the back of the copy sheet and the master sheet, depending on the facing of the sheets, causing the data to appear on the copy sheet.

The novel copy sheet utilizes in its preferred form a thin white sheet of paper coated on one side with a binder containing small amounts of heat-coliorable material consisting of a mixture of spirobenzopyran derivatives, benzoyl leuco methylene blue, thiocarbanilide as a color intensifier if desired, a fixing agent, urea, and buffering agents to keep the material at an approximately neutral pH and to eliminate premature fading.

'llhe transilluminating and reflex systems of use of the novel thermo-responsive copy sheet are shown in FIGS. 1, 2, and 3 in diagrammatic form, wherein the base web materials, the coating, and the data to be copied are represented. The systems of assembled sheets in FIGS. 1 and 2 are of use particularly with master sheets having data on but one side, whereas FIG. 3 represents a use of the novel copy sheet with a master sheet having data on both sides.

The infrared-heated data characters on the master sheet transmit their heat by conduction through the intervening base webs to the thermo-colorable coating of the novel copy sheet.

In the preferred and other embodiments of the invention, the materials which liorm the color immediately on being heated are substituted spirolbenzopyrans, the parent unsubstituted compounds having the molecular formula 1,3,3-trimethyl 2H-1'-benzcpyran)-2,2-indoline] and having the structure e--7 and benzoyl leuco methylene blue, which develops color in several hours after being heated or on exposure to sunlight; in addition, thiocarbanilide as a color intensifier, and materials, such as urea, which aid in fixing and blllffering the coating, of which examples are thiocarbanilide and N21 HPO .7H O. The preferred coating composition to be applied to the paper consists of about 85 percent water, Spercent colorab'le materials, including intensi- 7 fiers, and 10 percent fixing and buffering materials. Inert thickening materials, in addition, may be added if necessary to produce proper coating consistency. Various other substitutes for the colorable materials will be given after the following preferred coating-composition.

The following preferred coating composition is based on a total weight of 99.91 grams, but it may be enlarged upon for commercial batches:

Grams (a) The 6' nitro, 8 methoxy derivative of spirobenzop yran for which the structural tormula has been given 1.25 (b) Benzoyl leuco methylene blue 1.50 (c) Thiocarbianilide 2.50 (d) Nonylphenoxyethanol, sold now by Roihm &

Haas Company as a non-ionic surface active under the trade name Triton N- 0.16 (e) H O 55.50 (f) Urea 5.00 (g) Na HPO .7H O 3.00 (:h) Polyvinyl pyrrilidone of 300,000 molecular weight as a 15 percent aqueous solution 10.00 (l) Polyxinyl pyrrilidone of 50,000 molecular weight 1.00

(j) Oarbox-y vinyl polymer having a viscosity of 1,000 centipoises in a one half of one percent aqueous solution as determined by the Brookfield Viscosity Tester at 20 rpm 20.00

This composition is coated on a base web of paper of the desired thickness so that when dried, the coating has a thickness of 0.0005 of an inch more or less. The base web stock of the copy-receiving sheet and the master sheet should be of such a nature as to pass infrared light, if the reflex system of irradiation, as shown in FIG. 2, is used. In the reflex system of FIG. 3, only the base web of the copy-receiving sheet need pass infra-red radiation.

The preferred composition just given gives a dark blue color when heated. Following are sulbstituents which may replace the 6' nitro, 8' methoxy derivative in the given structural compound and which give shades of blue when heated with the other components:

6nitro, 8'-OC H 5-chloro, 6,8'-(NO 5-chloro, 6-nitro, 8-methoxy 8'-nitro To give a green color, the following substituents may be used:

8-methoxy 4,7,8'-(OCH To give a pinkish tone, the following substituents may be used:

5-chloro, 6-nitro 5-chloro-8-methoxy 6'-nitro Substitutes for benzoyl leuco methylene blue are:

Iso-valeryl leuco methylene blue Iso-butyryl leuco methylene blue Propionyl leuco methylene blue Substitutes for the sensitizer thiocarbanilide are:

Thiourea and its derivatives 1,1-diethyl-2-thiourea 1,1-diallyl-2-thiourea 1,3-dibutyl thiourea 1-allyl-3-phenyl-2-thiourca The binder, the butter, and the thickness for the coating composition are not critical, and their equivalents are many and should be well known to those skilled in the art.

Referring to FIG. 1, the copy sheet base web 20 of paper has the temperature-sensitive coating 21, which is overlaid by a non-infra-red-adsorbing master sheet 22 having thereon data 23 in carbon ink characters, or equivalent, that absorbs infra-red radiation from the source 24 and thereby becomes hot. The ink characters become heated :by the infra-red rays, whereas the base web of the master sheet does not become heated to any great extent, by either reflecting or transmitting the infra-red rays. The heat induced in the characters is proportional to the absorbed energy, and the infra-red source is so adjusted that the characters rise in temperature to a point where the heat is conducted through the sheet 22 in the pattern of the characters to cause coloration of the materials in the coating 21, as copied data 25. The thinner the master sheet web 22 is, the less the side diffusion of heat there will be, resulting in a sharper copy of the characters on the coated sheet 20.

FIG. 2 represents the same assembly of master sheet and thermo-sensitive coated sheet 20, 21, with the infrared radiation directed through the assembly from the rear of the copy-receiving sheet. The copy-receiving sheet and the master sheet base web, being non-in-fra-red-radiation absorbing, pass the radiation to heat the data characters, with a resultant copy 25 made on the coated side of the copy sheet. It is apparent that, the thinner and more transparent the base paper webs, the more distinct the copied data is.

FIG. 3 represents an assembly of a master sheet and the novel copy sheet wherein the master sheet has data on both sides and it is the intent to have a copy of the data of one side only. Here the back (uncoated side) of the copy sheet 20, 21 is placed against that side of the master sheet to be copied, and the infra-red radiation is passed through the copy sheet to heat the underlying data-representing characters, which become hot and transfer such inducedheat image, by conduction, back through the base web of the copy sheet to form the image on the thermosensitive coating thereof.

The materials used in the thermo-sensitive sheet are such as to insure stability in storage, either in the dark or in light of normal living environment, both before and after exposure, and the coating is relatively inexpensive compared to those heretofore known. The copy may be a dark blue color which appears on a substantially colorless (white) background, or the green or pink coloring dye may be mixed therewith, in combination from among those mentioned, in any proportions, or any of the dyes may be used alone. A suitable coloration of the master sheet or the data-receiving sheet may be chosen as long as it does not convert the applied infra-red radiation to heat.

FIGS. 1, 2, and 3 are exemplary systems only for illustrating the utility of the thermo-sensitive copy sheet, useful in copying data from a master sheet printed on one side or both, according to the mode of assembling the copy sheet with the master sheet and the direction in which the infra-red radiation is applied thereto.

What is claimed is:

1. A thermo-colorable record copy sheet consisting of a supporting web having a substantially colorless coating thereon which turns to a colored form when heated, said coating having as color ingredients a mixture of (a) the 6'NO 8' methoxy derivative of the compound having the structure and (b) benzoyl leuco methylene blue;

as a color intensifier thiocarbanilide; and

urea as a color fixer, all carried in a bufi'ered binder holding the coating substantially at a neutral pH.

2. The record sheet of claim 1 in which the supporting web is a thin sheet of material and the coating thereon is not colorable by infra-red radiation.

3. The record sheet of claim 1 in which the supporting web is paper that is not heated by infra-red radiation directed thereon.

4. The record sheet of claim 1 in which the supporting web is substantially transparent to infra-red radiation.

5. A thermo-colorable record sheet consisting of a supporting web having a substantially colorless coating on a surface thereof which turns to a colored form when heated, said coating having as color ingredients (a) at leasttone of the derivatives of the compound 1,3,3 trimethyl spiro[(2H-l'-benzopyran)-2,2 indoline], having the structure wherein said derivatives are compounds represented by said structure-in which selected ring positions are substituted with selected radicals, said radicals being selected from the group consisting of S-chloro, 6- nitro; 8-ethory; 5-chloro, 6'-nitro, 8'-ethoxy; 8'- methoxy; S-chloro, 68'-dinitro; S-chloro, 8-methoxy; 6-nitro, 8'-methoxy; 5-chloro, 6-nitro, 8-methoxy; 8-nitro; 6-nitro; and 4,7,8-trimethoxy;

(b) at least one compound selected from the group consisting of benzoyl leuco methylene blue, iso-valeryl leuco methylene blue, iso-butyryl leuco methylene blue, and propionyl leuco methylene blue; and a buffered binder material holding-the coating substantially at a neutral pH.

6. The record sheet of claim 5 in which the web is paper.'

7. A liquid coating composition consisting of an aqueous vehicle containing at least one derivative of 1,3,3-trimethyl-spiro[(2H-l benzopyran)-2,2' indoline] having the general structure wherein said derivatives are compounds represented by said structure in which selected ring positions are substituted with selected radicals, said radicals being selected from the group consisting of S-chloro, 6'-nitro; 6'-nitro, 8-ethoxy; S-chloro, 6,8'-dinitro; 5-chlor0, 8-methoxy; 6'- nitro, 8-methoxy; S-chloro, 6'-nitro, 8-methoxy; 8'-nitro; 6-nitro; and 4,7,8-trimethoxy; at least one compound selected from the group consisting of benzoyl leuco methylene blue, iso-valeryl leuco methylene blue, iso-butyryl leuco methylene blue, and propionyl leuco methylene blue; and a buffered binding material holding thecomposition at a substantially neutral pH.

8. A liquid coating composition comprising: (a) a major proportion of water, (b) a minor proportion of the temperature-colorable material 1,3,3 trimethyl 6-NO ,8'-methoxy spiro 5 [(2'H-1'-benzopyran)2,2 indoline] having the structural formula H30 c H 3 (c) a minor proportion of a leuco methylene blue compound selected from the group consisting of benzoyl leuco methylene blue, iso-valeryl leuco methyl- 6 ene blue, iso-butyryl leuco methylene blue, and propionyl leuco methylene blue; and a buffered binding material holding the composition at a. substantially neutral pH.

References Cited by the Examiner UNITED STATES PATENTS 2,880,110 3/1959 Miller 117-36.7 3,020,171 2/1962 Bakan et al. 11736.2 10 3,111,407 11/1963 Lindquistet a1 11736.7

MURRAY TILLMAN, Primary Examiner. LEON J. BERCOVITZ, Examiner. 

1. A THERMO-COLORABLE RECORD COPY SHEET CONSISTING OF A SUPPORTING WEB HAVING A SUBSTANTIALLY COLORLESS COATING THEREON WHICH TURNS TO A COLORED FORM WHEN HEATED, SAID COATING HAVING AS COLOR INGREDIENTS A MIXTURE OF (A) THE 6''NO2, 8'' METHOXY DERIVATIVE OF THE COMPOUND HAVING THE STRUCTURE 